1. Field of the Invention
The present invention relates in general to a rotary cutting saw, and more particularly to such a rotary cutting saw of so-called “dry-cutting type” which is used for cutting or parting a pavement surface.
2. Discussion of the Related Art
In a road construction or restoration, a pavement surface is cut or parted by using commonly a rotary cutting saw including a circle-shaped base disk and diamond cutting chips which are attached to an outer circumferential surface of the base disk. In a dry-cutting operation in compared with a wet-cutting operation, the cutting saw is less cooled so that the cutting chips are more likely to be burned due to generation of heat at their side surfaces, which are rubbed against a cut surface of the pavement since the cutting saw tends to suffer from an axial runout or a side-wall runout due to cutting resistance exerted to the cutting chips. Further, if each cutting chip is worn at its side surfaces to such an extent that causes side or axially opposite end surfaces of the base disk to be brought into contact with the cut surface, the base disk is heated whereby its blade tension is undesirably reduced.
In view of the above-described problems, there is proposed an arrangement which is provided on the axially opposite end surfaces of the base disk of the cutting saw and which serves to restrain wear of the base disk and contact of the base disk with a cut surface of a work material. Examples of such an arrangement are disclosed in JP-A-H07-40252 (publication of unexamined Japanese Patent Application laid open in 1995), JP-B2-3236550 (publication of Japanese Patent issued in 2001) and JP-A-H05-57619 (publication of unexamined Japanese Patent Application laid open in 1993).
In each of the disclosed examples, the rotary cutting saw includes, in addition to the diamond cutting chips as major cutting chips attached to the outer circumferential surface of the base disk, diamond cutting chips as auxiliary cutting chips are provided on the axially opposite end surfaces of the base disk, so as to cut side surfaces of a cut slot of the work material, for thereby avoiding the base disk from being rubbed against the work material and accordingly preventing the base disk from being worn. The provision of the auxiliary cutting chips also serve to reinforce the base disk. This arrangement makes it possible to prevent wear of the base disk, but is not effective to prevent burning in the major cutting chips, which is problematic particularly in a dry-cutting operation. Further, since the auxiliary cutting chips provided on the axially opposite end surfaces of the base disk cut the side surfaces of the cut slot, namely, the width of the cut slot is increased by the auxiliary cutting chips, the cutting saw becomes more movable within the cut slot in its axial direction, thereby making it impossible to restrain the axial runout of the cutting saw.
In a dry-cutting operation, the axial runout of the cutting saw leads to reduction in the cutting performance due to heat generation and wear of the cutting chips. Therefore, for assuring an excellent cutting performance of the cutting saw, an improvement in its heat dissipation performance and a reduction in the axial runout of the cutting saw are needed.